What's the difference between why not doing it and why not doing it?

The difference between why not do it and why not do it is as follows:

1, why can't not be a sentence alone, but why can't not be a sentence alone?

2. Why not have three main meanings:

(1) can be used to ask why: Why?

You shouldn't smoke. You shouldn't smoke. B: Why not? Why?

(2) stick to your own point of view

Example A: Do you really want to sue them? Do you really want to sue them?

Yes, why not? Yes, why not?

(3) express consent

Example a; Can I go with you? Can I go with you?

B: Why not? Why not? (good)

3. Why not? Why don't you ...? Express suggestions or opinions

Why don't you ask Dr. Yang? Why don't you ask Dr. Yang?

That's a good idea. That's a good idea.

Extended data:

example sentence

(1) What? What about you? Need? Is it? Answer? Change? Yes? Scene. ? Why? Isn't it? Going? Open? Answer? Cruise?

You need a change of scenery. Why not travel by boat?

(2) Why? Isn't it? Really? Answer? Try it?

Why not give it a try?

(3) Want? Where to? Consumption? That? Afternoon? With what? Me? ? —? Why? Isn't it? ?

"Do you want to spend this afternoon with me?" -"Good!"

(4) Why? No? What about you? Inquiry? By who? Telephone?

Why don't you call and ask?

(5) Why? No? What about you? Coming? And then what? See? Me? At some point?

Why don't you come to see me sometime?

(6) Why? No? What about you? See? What if? What about you? Is it okay? Scared? Up? Answer? Cup? Yes? Coffee?

Do you think you can at least make a cup of coffee?